A personal safety system with a security entrance and with a holding room is known from DE 35 21 884 C1. The prior-art personal safety system also comprises a ventilation and air exhaust system including a filter unit.
Prior-art personal safety systems are designed such that persons who enter the security entrance must stay therein until possible contaminations have been reduced to a permissible level. An air delivery unit, which flushes the security entrance and sends the gas over a toxic gas filter, is provided for decontamination. The degree of contamination can be determined by measuring the toxic gas concentration in the security entrance. The interior space may be entered only when the contaminations have been reduced to a permissible level. The security entrance must be as small as possible for fast decontamination, which means that only a small number of persons can stay in the security entrance. This security principle is not suitable for the case of a disaster with highly toxic gases, because persons who want to enter the security entrance wear an escape hood, which offers protection for a very limited time only. This means that persons cannot wait for entry at the outer door of the system because of time limitations. The duration of use of an escape hood is often limited to a period of 30 minutes. A fairly large number of persons can be expected to want to enter the holding room at the same time in case of a disaster.